Operating mechanism for retractable members on board aircraft such as landing gears, cupolas, tanks, etc.



" Feb; 28, 1939.

c. R. W ASEI GE 2,148,972 v TRACTABLE MEMBERS ON BOARD AIRCRAFT Y OPERATING MECHANISM FOR RE SUCH AS LANDING'GEARS, CUPOLAS. TANKS, E TC 6 Sheets-Sheet 1H Filed Feb. 16, 1957 v v Unveni'or. (llml-leslla mondllds g@ M.

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' Feb. 28, 1939.f

OPERATING MECHANISM FOR RETRACTABLE MEMBERS ON BOARD AIRCRAFT 28, 1939. Q R WA E GE; 2,148,972

OPERATING MECHANISM FOR RETRACTABLE MEMBERS ON BOARD AIRCRAFT SUCH AS LANDING GEARS, CUPOLAS, TANKS, ETC

. Filed Feb. 16, 1937 6 Sheets-Sheet 5 Unvenior.

Clw 'les Raymond Waw'g a; 61 WW c. RAWASEIGE 2,148,972 OPERATING MECHANISM FOR RETRACTABLE MEMBERS on BOARD AIRCRAFT sucn As LANDING GEARS, CUPOLAS, TANKS, ETC I Filed Feb. 16, 1937 6 Sheets-Sheet 4 Q & h A t I I 1 l I HI I t 11" W Q Q\ Q & S

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FeBJ2s, 1939."

'Feb.28,1939. RW SEIGE 2,148,972

OPERATING MECHANI$M FOR RETRACTABLE MEMBERS ON BOARD AIRCRAFT SUCH AS LANDING GEARS. CUPOLA'S, TANKS, ETC

Filed Feb. 16, 1937 6 Sheets-Sheet 5 3n ven To Charles Raymond 51 Hornet} Feb. 28,- 1939 Q R wASElGE 2,148,972

OPERATING MECHANISM FOR RETRACTABLE MEMBERS ON BOARD AIRCRAFT SUCH As LANDING GEARS, CUPOLAS, TANKS, ETC

' Filed Feb. 16, 1957 6 Sheets-Sheet 6 M v F A x C/zarZes agllwfld, Was ejg'e,

Patented Feb. 28, 1939 UNITED STATES PATENT OFFICE OPERATING MECHANISM FOR RETRACT- ABLE MEIWBERS ON BOARD AIRCRAFT SUCH AS LANDING GEARS, CUPOLAS,

TANKS, ETC.

Application February 16, 1937, Serial No. 126,082 In France February 18, 1936 20 Claims.

The present invention has for its object an operating mechanism for retractable members on board aircraft, such for example as landing gear, trailing wheels, turrets, tanks, cupolas etc.

Themechanism which is the object of the invention essentially comprises a movable driving device which is compelled to follow a definite path and which has a driving member proper and a speed reducer interposed between two members between which the power is applied, one of said members being coupled or fixed to a fixed part of the aircraft and the other being coupled or fixed to the member to be moved or even consisting of said member itself.

The mechanism thus formed has the great advantage of having a very great flexibility of adaptation on an aircraft which is already constructed or which is being designed.

Such a mechanism is capable of very varied embodiments. In one group of embodiments the movable driving device is arranged at one of the summits of a polygonal line forming the contour of "a deformable system materialized by bars arranged along said contour, the driving device being coupled between the two bars which end at said summit. The deformability of the system at each of the summits can be obtained by simple articulations, slides or a combination of "the two.

For the sole purpose of facilitating the comprehension of the invention, there have been shown in the accompanying drawings, but solely by way of indicative and non limitative examples a few" examples of embodiment which furthermore offer other peculiarities forming as many detail objects of the invention.

Figs. 1 to 6 show diagrammatically the application of various modifications of the mechanism which is the object of the invention to different systems of raising the landing gears of aeroplanes, Fig. showing the mechanism applied to a trailing wheel; 'Fig. 7 is a diagrammatic section of a particular embodiment of the driving articulation in the case of a deformable system constituted by a compass, said section being taken through the axis of articulation.

Figs. 8 and 9 are similar sections to that of 'Fig. 7 but show modifications of construction.

Fig. 10 shows in section a detail of an articulation which exerts drive in both directions of rotation.

' Fig. 11 shows diagrammatically another modification of the operating mechanism according to the invention.

Fig. 12 is a diagrammatic view of a particular locking device.

Fig. 13 shows diagrammatically a modification of the unlocking control and Fig. 14 is a section along the line AB.

Fig. 15 is a perspective view of another construction of driving articulation with partial section, partly broken away.

Fig. 16 shows a section through the driving spindle of a modification of construction of Fig. 15.

Fig. 17 is a partial View of the mechanism of Fig. 15 and shows a torsion bar device.

And Fig. 18 is a corresponding side elevation.

In the example of Fig. l the landing gear lifting system is of the lateral type, that is to say that the wheel i is carried by one end of a shock absorber 2 of which the other end is hinged on a pin 3 directed substantially from the front towards the rear. Two bars 5 and 5 which are hinged to each other at 6 form a sort of compass of which the arm 4 is hinged at I on a fixed point of the shock absorber 2 and the arm 5 on a fixed point 9 of the framework of the aeroplane. lfi designates the driving device as a whole which is arranged at the hinge 6 and coupled between the two arms 4 and 5. It is obvious that when the compass 45 closes under the action of the device Iil to come into the position shown in dotted lines, the wheel l passes from the lowered position I to the raised position II. In this example the two members 6, 5 between which is coupled the driving device I 6, are formed the one by the bar 4 which is coupled to the member to be moved I, 2 and the other by the bar 5 which is coupled to a fixed part of the aircraft. The members 4, 5 and 9 form a deformable system of polygonal contour materialized by bars which are articulated at the summits of the polygonal line and which are all movable.

In the example of Fig. 2, the wheel I is raised by pivoting from the front to the rear about a pin 3 which is transverse to the longitudinal axis of the aeroplane and it is carried by said pin through the instrumentality of a shock absorber fork 2' (Fig. 4). The mechanism which is the object of the invention is the same as in the case of Fig. l, but the compass se is arranged behind the fork 2' and the whole arrangement operates in the same manner to cause the wheel I l to pass from the position I to the position II.

In Fig. 3 the lifting system of the wheel I is of the same type as in Fig. 2, but the wheel is lifted by pivoting from back to front and the compass 4, 5 is arranged in front of the fork 2'.

Fig. 5 shows the application of the mechanism which is the object of the invention to a trailing wheel II carried by a fork 4 which is hinged on a bar 5 of which the other end is hinged at 9 on a fixed point of the aeroplane. The driving device If! is arranged at the hinge connection between the two bars 4 and 5' and bears on a cradle I2 when the Wheel is lowered to the landing position I. A supplementary bar I3 which is hinged on the fork 4 and on another fixed point I4 of the aeroplane, completes the definition of the mechanism and compels the wheel I I to follow a definite path. The operation is the same as in the previous cases and the wheel is displaced almost vertically to come into the position 11.

In this example the bars 4', 5' and I3 form a deformable system of polygonal contour having bars which are articulated at the different summits and which are all movable but one of the two members 4, 5 between which is interposed the driving device III, is in this case formed by the member to the moved 4' itself.

Fig. 6 shows another example of mechanism according to the invention applied to the raising of a landing wheel arranged like that of Fig. 2. The driving device I0 is in this case interposed between the end of a bar 5 of which the other end is hinged on the wheel carrier fork 2 and a bar 5 fixed on the aircraft, said bar. carrying a rack I4 engage-d by the speed reducer of the driving device III. The latter therefore moves along the rack which determines its path. In this case again, the members 4 5 and 2 form a deformable system determining a polygonal line, but in this case the deformation of the system is obtained at the summit on which it located the driving device ID by the sliding and pivoting of one of the two members between which the driving device I0 is interposed, viz. the movable bar 4, on the other of said two members which is fixed, in particular the bar 5.

In the example of driving articulation shown in I Fig. 7, a substantially cylindrical housing I5 placed between the two arms 5 of a double compass is fixed to said two arms; another housing I6 partially surrounds the housing I5 and is fixed to the two other arms 4 of the compass. The inside of the housing I5 carries the stator I! of an electric motor of which the rotor I8 is arranged along the hinge pin 6 of the compass and is journalled in bearings I9 of said housing. At

the end of the shaft 20 of the rotor I8 is keyed a torque limiting clutch 2| operating by friction and by means of centrifugal weights 22 carried by the driving member, whereas the driven member is .fixed on a shaft 23 which is co-axial with the rotor. Said shaft 23 engages a reducer of the epicycloidal type comprising a pinion 25 keyed on the spindle 23 and meshing with peripherally spaced planet members 26, each planet member consisting of a pinion having two toothings 21, 28 which roll respectively on a toothing 29 fixed to the housing I6 and on a ring gear 30 rotating with the driving member 3|, free on the spindle 23 of a free wheel of which the driven member 32 rotates in unison with the housing I6 to which it is attached by a sleeve 33 projecting from the housing I5.

On the other hand, rocking latches 35 are carried by the housing I5 and cooperate with suitable. keepers carried by the housing I6. Said latches 35 are urged towards their locked position by springs 36. Preferably the housing I5 carries pairs'of keepers 31 spaced apart the angle of opening of'thecompass so that the same latches find keepers opposite them when the compass is completely open and when it is closed.

Each latch 35, Figure '7, furthermore carries an appendix 38 which extends inside the housing I5 and terminates adjacent the spindle 23 so that it is in the path of a; sliding sleeve 39, which fingers 40 carried by the weights 22 push back axially when said weights move outwardly responsive to centrifugal force, the displacement of the sleeve causing the latches 35 to rock against the action of the springs 35 and to become disengaged from the keepers 37.

It is obvious that When the latches 35 are engaged in keepers 31 the two housings I5 and I6 are held stationary relatively to each other, thereby locking the hinge and the compass in its open or closed position. If the electric motor I1, I8 is started up, the weights 22 begin to move apart as soon as the first revolutions of the motor occur and cause the unlocking in the above described manner. Said weights are constructe so that said unlocking is effected before they begin to bear sufliciently on the torque limiter clutch to cause the shaft 23 to be driven. After the unlocking is effected and as the weights continue to move apart responsive to the increase of speed of the motor, the shaft 23 is drivenanda relative angular displacement of the housings I5 and I5 occurs and consequently of the arms dand 5 of the compass to which said housings are respectively fixed. At the end of the stroke, a finger 32 carried by the housing I6 actuates a switch 43 controlling the motor and cuts off the current. As the motor stops, the weights 22 move towards the centre and enable the latches 35 to rock under the action of the springs 36 to penetrate into the'keepers 31 located opposite them and to lock the compass in the new position which it has taken up.

The presence of a centrifugal coupling which is totally disengaged when inoperative also has the advantage. of enabling the motor to start on no load, thereby eliminating the very high current peak at the instant of starting with rapid electric motors, said peak being particularly disadvantageous on an aeroplane in which the batteries are of low capacity.

At the time the driven shaft '23 is driven, the rotor of the electric motor has moreover acquired an appreciable momentum which helps to the landing gear or other member to be operated.

is in the low position and at a minimum when said member is in the high position. In this case it is advantageous to provide a braking device for the lowering, preferably a hydraulic dashpot established so that at the beginning of the lowering said braking is weak, to increase subsequently and fall again to a very low value at the end of the lowering so as to enable the looking to be effected. The. device for storing energy during the raising can be arranged on the hinge itself.

Of course a motor operating in two directions can be used without interposing a free wheel, the hinge in that case exerting drive in both directions.

It is advantageous to also provide a disengageable, coupling between the driven member of the reducing gear and the corresponding arm of the compass so as to permit ofthe operation of the hinge by auxiliary means in spite of the i'rreversibility of the reducing gear.

, In the case of a motor operating in two directions the presence of a free wheel is likewise desira'ble in order to permit 'of a relative angular displacement of the two housings I and I6 at a higher speed than the speed of the electric motor would permit; it is in that case necessary for thereto be a locking device for the 'free wheel so that the hinge can exert drive in both directions. It is particularly advantageous to arrange two free wheels adapted to act in opposite directions and associated with a device capable of locking one or the other of the Tree wheels at the same time as it "releases the other. Fig. shows an example of such a mechanism. In this example the driving member 3| is surrounded by a collar 50 with which it engages by means of ribs 5| engaged in grooves of greater width 52 of the collar 50, so that the two parts 3| and 50 can undergo a relative angular displacement with respect to each other. The collar 50 has on the outside fiat portions 54 and in the space between each fiat and an outer crown 55 are lodged two balls 56 and 56 held apart by a spring 51 and retained in a cage 58 with a slight circular play. Pawls 59 which are pivoted on the collar 50 have one end engaged in recesses of the cage 58 and the other endin recesses of the part 3|. It is obvious that as the part 3| rotates in the direction f and consequently tends to drive the collar 50 in the same direction, the pawls 59 tend to remain in the position which they have in Fig. 10, tending to rotate the cage 58 in the opposite direction to f and to jam the balls 56 between the outer crown 55 and the flats 54, thereby causing the crown 55 to be driven in the direction i when the part 3| rotates in the opposite direction to f, the angular displacement of the ribs 5| in the grooves 52 causes the pawls 59 to pivot and consequently the cage 58 to be displaced, thereby tending to lock the balls 56 and to drive the crown 55 in the opposite direction to f. On the other hand when the crown 55 is the driving member it can rotate as a free wheel in either direction as soon as its angular speed tends to be greater than that of the member 3|, without the balls 56 and 56 tending to jam.

v In the modification of Fig. 8, latch keepers 31 are provided in a slide 60 guided on the housing l5 and form a nut on an axially fixed screw BI carried by the housing I5. Pinions 62 at the end of said screw mesh with toothed segments 63 fixed on bars 50. When the compass formed by the bars 4 and 5 opens or closes, the pinions 62 are rotated and the slide 60 is displaced axially to bring one or the other of the keepers 31 opposite the latch 35 so as to permit locking to be efiected in two extreme positions of the compass. The slide 60 serves furthermore to actuate the end stroke switch 43'. There is no housing I 6 in this case and the two arms 4 and 5 are caused to rotate in unison through the intermediary of the screw 6|. is the same as that of Fig. 7.

In the modification of Fig. 9 the reducing gear I0 is arranged right at the end of the housing I5 and the wheels II are placed in the space between the reducing gear and the motor so as to engage the housing I6 towards the middle of the latter In other respects the mechanism priate part of the housing I6.

Fig. 11 shows an example of construction of the embodiment shown diagrammatically in Fig. 6. The driving device enclosed in its housing I5 drives a shaft I5 which projects from the said housing and on which is keyed a wheel 16 meshing with a wheel 'I'I keyed on the end of a countershaft I8 parallel to the axis of the motor and carried on the outside by the housing I5. On the other end of the shaft 18 is keyed a wheel 19 which is;

identical with the wheel TI, and the wheels I! and I9 mesh respectively with racks 80 fixed on two channel irons 8I which between them form the bar 5 of Fig. 6.

At the two ends of the housing I5 are furthermore fixed roller bearings 82 engaged in guides or races 83 carried by the channels BI. It will be realized that when the motor rotates the wheel 16, the driving device as a whole runs along the racks 80.

As seen in Figs. 1, 2, 3 if the landing gear in the raised position is subjected to great forces of inertia, the locking arrangement of the hinge i0 is subjected to very great reactions. To avoid them it is advantageous to provide the locking in the raised position directly between the bars 4, 5 as shown in Fig. 12, for example by means of a hinged latch 85 fixed on a bar and engaging in a catch 86 fixed on the other bar. In this manner not only the hinge I0 is relieved, but the bars 4, 5 .are no longer subjected to bending stresses in the raised position. The unlocking of the device shown in Fig. 12 can be controlled by the driving device or by an electro-magnet acting directly, or by an auxiliary mechanical control.

In this case, and in general when the automatic unlocking of the driving hinge is only provided for one direction of operation, a modification of the control device for the latches consists (Fig. 13) in making the crown 29 capable of an angular displacement which is limited between 3 two stops, said angular displacement causing,

through the instrumentality of a cam 81, the retraction of the latch 35, either by direct-action or through the instrumentality of any appropriate transmission by cable, rods, countershafts, etc. in particular if the latch is remote (latch 85 Fig. 12)

In the example of construction of Fig. 15, the gear wheel 30 which is driven by the planet gears 26 of the reducing gear, carries a crown of dogs 90, and another crown of dogs 9| inside the crown 90 is carried by a plate 92 located at the end of a pinion 93 which is loosely mounted on the drive shaft 20. Said pinion 93 meshes with a gear wheel 91 carried by a shaft 98 fixed on the housing I5; the wheel 97 meshes with a ring of teeth 99 carried inside the housing I 6. 0pposite the dogs 98 and 9| is arranged another crown of dogs we carried by a plate Iill loosely mounted and sliding on the hub of the plate 92. Said dogs IEO are arranged so as to be able to be placed in engagement both with the dogs 90 and with the dogs 9! thereby causing the pinion S3 and the sun wheel 30 to rotate in unison. Between the. plates 92 and IilI are interposed springs I02 which tend to move said two plates away from each other.

As long as the crown I00 is prevented by the springs I02 from engaging simultaneously with the crowns of dogs 90 and 9|, it is possible to displace the housings I5 and I6 angularly in both, directions relatively to each other about t ei" on hinge '6', and consequently the bars whichthey are respectively fixedisince, in th s movementfthe pinion 93 and the gear wheel"9lrotate loosely and the'reducing gear asa whole remains stationary. On the contrary wh n, thefdogs 9D 9 !.arje in engagement, theiribility of the reducing gear renders any ular displacement impossible otherwise than he action ofthe drive shaft 28 I13 formed by rods slidingly mount ed irfguicles 1M carried by the housing I5 are arrangedpa'rallel'with the axis of the housings I5 l6v so as toenable them to push the 'plate I against the action of, the sprin s I92 and o ffthe sprin gs IU pla'ced between thefixed'guide's I'Ilgl and a shoulder I 95 on each pushrod.

Other much stiffer springs I07 are interposed be ween the other face of saidshoulder I96 and th collar of a sleeve I93 mounted on the, shaft illfand pushing said sleeve against rockin finigers II l carrieolbya part I I2; keyed on the drive shaft The fingers IIjI carry weights U3. arranged so that in 'moving'away from the axisot rotation theycaIlSQ thesleeve LUB tO Ice pushed 7 by the fingers III against the action of the springs'llll and thereby causethe push rods It]; to silide'agai st the "action o f thesprings I 515, The leev '68, he m re carries nloc o es lil l {ooperatir g with rollers I of the latches arranged radially inthe housing I 5 to en a e in keepers 3'I o i"the"housing I hand urgedtowards their looking position by springs 35,

'When the shaft, isdriven by the motor I8,

,. the'i oentrifugal clutch 22 first of all comes into att'ior jtne reducing gear 2s st is driven and the crown of dogs Sllrot'ates loosely. At the same ti" 'e t'heweights' H3 move apart, thenngers H I p] h th'sleeve" IUB inthe direction 1 and, in this ement, the unlocking slopes IN bring the la c es" b a' ck, towardsthe centrethereloy enabling the'housings i5 and Ittorotaterelatively toeach other. Then, as the latches 35 are dis,- engaged, the weights III continue to move apart carrying with them the sleeve Hi8 and displacing the push rods I 9 3 t hro1 1gh the 'instrumentality ofisprings Iil'l, compressingthe springs I95. Ihe

push'rods Illfidisplace the plate Iill, compressing th f'springs I02 and; the dogs I0 5. engage in the dogsfliland 9!: The pinion 93 is then f driven andiotatesthe housing ISthrough the, instrumentality ofthe gear wheels 91.

When the motor flastops, the weights H3 move towards the aXis'thesprings IllZpush back the plate IIlI whereas the push rods 53 are reneme is the opposite direction to feby springs I05 and carry with themthe sleeve IE8; the dogs Ill}; disengagefromthe dogs Silland 9! thereby breaking the coupling between the pinion 93 and the reducing gear i. e. the transmission interposed betweenthe housings I5 and I6. Then as tllefsleeve lll 8'co'ntinues to move backwards under' the'pressure of the springs I85, the unlockmg slopes H4 release the latches 35 which the springs 36 push into the keepers 31 as soon as any of" them comes into register with thelatches.

Saidkeepersare arranged so that there is only one" position of locking of the lowered landing gear and'that there is no locking of the gear when. theda tter is raised again; the lowering of the gear is therefore always possible even if the electric motor does not operate.

On the other hand, it will be seen that the actions o f the latches 35'and of the plate I Ill are stiictlysuccessive, and in bothdirection s. There seems cannottherefore any engagement. of the crown I'D JFb ford thelatches' 35; haveiijcom'e; out of the keepers, 'andfconyerse1y- Any risk'of mistake in operationisthus'elirninated. Thehous ingf I5 is' fixedby its end at, the end of a cylinder I2Il'whichisbolted on the arm 5f'o'f the comp ass likehinge. Inside said cylinder can rotate adiametral paddle I2! of which the hub is extended outside the cylinder, by a tail I22 which. passes through the hinge Sand on which is keyed a lever I23 of which the end is fixed on the bar, 4.' Insidej'thef cylirider IZfiis another paddle I2 4 which canonly be displaced between two stops IZlSand I26 formed by the edges of a recess of, greater cliameter of the cylinder I29. The pad-'-' dle IMeXtends to; the bottom of'said re'cejss but. it has; on one of its faces a flange o-fithe same. diameteras the rest of thecylinder I20.

"Radial holes IZTin the hub of'the Paddle]?! place each of I the four compartments between said paddles I2 I I and; I24,in communication with a central bore 128 of the tail I22 anda' piston valve I29;scrwedf in said boreenables the cross section of the passage through saidlholes, to be adjusted. Saidfpiston valvejl29is' constructed and5', thel paddle IZIand the cylinder I20llikea wise rotate relatively 'to each other and.'the paddle l2fl 'followsp this movement until "itfis stopped by'one of the stops'l25 and. I26 according'toithe direction of rmovement Aslong asithepaddle I24 rotates, no braking takes place 'whatever be the direction of the paddle I2 I when such direction is that of the arrow] and the paddle v I 24 is held stationary, by thestopIZfijwhichprevents it fr0m rotatmg furtherin thedirection of f; the liquidvwhich is' compressed byfthe' front' face. of thefpaddle I2 I",

lifts the valve I 3| and escape'sthrough the hole I30 in thedirection fl there is therefore as yet no braking; itislon'ly wheh 'the direction of 1'0: tationo f thelpaddle I 2I isiin the Opposite dire'ction tof'and' thepaddle I24 is held stationary by the stop 126 that the liquid which is compressed by the front face of the paddle circu latesfin the direction of the arrowfflin the radial holes l z'l and brakes the relative displacemerit of th'e cylinder Land of the paddle I2].

Towardsthe end of its stroke the paddle I2I comles'into register with the 'part.of the cylinder greatest. i m ter he bvs n hejbr ing. on the other h nd at theinstant when the paddle' l2l approaches the stop I26, the flang e provided'on theface of said paddle forms with the adjacent stopasubstantially closed'cham ber. so that the liquidrwhich is therein damp's the impact of the paddleonithestop;

It will therefore be seen that the closing movements of the compass which correspond to the lifting of, the member to beretracted are not braked, whereasthe reversemovements which correspond to the lowering are strongly vbraked save at thebeginningandat the.end..

'In the modification of construction'ofFig. 16,. the sun wheel2'lf o f.the reducing gear is loose and carries on its sidea crown of dogs in;

e -ot rwas.5

ing] I5. Opposite said crowns 90' and 9| is another crown of dogs I00 which is mounted so as toslide axially. The dogs I00 are arranged toeng'age at the same time in the dogs 90' and 9|, thereby uniting the wheel 21' and the fixed. crown 9|, 1. e. holding said sun wheel 21 stationary. It is this crown of dogs I00 which in this case receives the action of the push rods I03 which are driven as in the construction of Fig. 15. On the other hand the pinion 93 is in this case constantly secured to the toothing 30' mesh-- ing with the toothing 28 of the planet wheels 26.

When the dogs I00 are not in engagementwith the dogs 90' and 0| the housing I5 can. rotate freely relatively to the housing I6, the crown 90 rotating loosely. When said dogs are in engagement, there can only be a relative displacement of the housings I5 and I6 through the action of the motor I8, owing to the irreversibility of the sun wheel reducing gear.

.In these. two examples of construction, each arm 4, 5 of the compass is double, i. e. each is comp'osedof two parallel arms connected to each other by a tubular cross member I30 crimped for example in said arms and it is said tube I30 which angularly ties the housing I6 to the arm 4 passing through an eye I3I of said housing I6.

In Figs. 17 and 18 the inner mechanism of the hinge which is that of Fig. 15 has not been shown and only the energy storing device has been illustrated. The latter consists of a bar I40 lodged inside the tubular cross member I30 of the arm 4 and of which one end is fixed to one of the limbs of said arm 4; for example by screws I4I engaging in longitudinal slots of the member I30. On the opposite end which passes through the other limb, is fixed preferably by means of splines, a crank I42 of which the crank pin I43 also forms the crank pin of another crank I45 pivoted on a pivot I46 fixedon the arm 5.

. The two arms 4, 5 of the compass and said two cranks I42, I45 as a whole, form an articulated quadrilateral of which the pivots'are formed by the bar I40, the crank pin I43, the pivot I46 and the hinge O itself of the compass. When-the compass 4,5 opens or closes it consequently causes a rotation of the crank I42 about the spindle of the bar I40 and the latter is twisted. Starting from the position of complete opening of the compass shown in full'lines in Fig. 18, the bar I40 is twisted in the direction I when the compass begins to close and it thus resiliently opposes such closing which corresponds to the beginning of the raising of the member to be operated. Then when the pivots I46 and I43 pass into a straight line (position II Fig. 18), the rotation of the crank I42 is reversed until the complete closing of the compass (position III). During this movement, which corresponds to the end of the raising, the bar restores the stored up energy and helps in the raising operation by relieving the motor of the hinge. During the opening of the compass, in other words during the lowering, the reverse takes place: from the position III to the position II the bar I40 acts as a resistance then it becomes a driving member from II to I, i. e. at the end of the lowering and compensates the decrease in action of the weight and the increase of the resistance of the air. It thus forms a safety member during the lowering.

The invention is of course not limited to the details of construction illustrated or described. Thus the latches can be controlled electro-magspeed reducer actuated thereby, tie means carried by said motor, further tie means connected to said speed reducer to be actuated thereby, both said tie means providing the one for connection of said unit to a stationary point, the other for connec tion of the unit to the retractable member to be operated, to thereby compel said unit to follow a predetermined path, and a clutch interposed between said speed reducer and the tie member to be actuated by said reducer.

2. Operating mechanism for retractable projecting members on board aircrafts, comprising a movable driving unit including a motor and a speed reducer actuated thereby, tie means carried by said motor, further tie means connected to said speed reducer to be actuated thereby, both said tie means providing the one for connection of said unit to a stationary point, the other for connection of the unit to the retractable member to be operated, to thereby compel said unit to follow a predetermined path, automatically operating latches carried by said movable unit, keepers adapted for engagement with said latches provided to'thereby lock said mechanism in at least one predetermined position, a centrifugal clutch between the motor and the reducer and including flying weights, and means whereby said weights are adapted to unlock said latches before causing engagement of said clutch.

3. Operating mechanism for retractable projecting members on board aircrafts, comprising a movable driving unit including a motor and a speed reducer actuated thereby, tie means carried by said motor, further tie means connected to said speed reducer to be actuated thereby, both said tie means providing the one for connection of said unit to a stationary point, the other for connection of the unit to the retractable memher to be operated, to thereby compel said unit to follow a predetermined path, and a free wheel between the speed reducer and the tie member driven thereby.

l. Operating mechanism for retractable projecting members on board aircrafts, comprising a movable driving unit including a motor and a speed reducer actuated thereby, tie means carried by said motor, further tie means connected to said speed reducer to be actuated thereby, both said tie means providing the one for connection of said unit to a stationary point, the other for connection of the unit to the retractable member to be operated, to thereby compel said unit to follow a. predetermined path and means adapted to act as a free wheel device in both directions of rotation between the speed reducer and the tie member driven thereby.

5. Operating mechanism for retractable projecting members on board aircrafts, comprising a movable driving unit including a motor and a speed reducer actuated thereby, said speed reducer being of the planetary type and including a driving sun wheel and a driven sun wheel, means adapted to alternately lock against rotation and make loose said driven sun wheel, tie means carried by said motor, further tie means connected to said speed reducer to be actuated thereby, both said tie means providing the one for connection of said unit to a stationary point, the other for connection of the unit to the re 6* tractable member to be ep'erated, re thereb yeom pel said unit to follow a predetermined path,

6. Operating mechanism as in claim 5, iurther comprising means including flying members rotated from said motor and connected to said looking means to operate same in dependence on the motor speed.

7. Operating mechanism as in claim 5, further comprising latches carried by said movable unit, keepers adapted for engagement with said latches to thereby lock said mechanism in at least one predetermined position, means including flying members rotated from said motor and Connected both to said latches and locking means so that 1 centrifugal movement of said flying members will first operate the latches to unlock the mechanism and thereafter actuate said locking means to lock the driven sun wheel against rotation.

' 8. Operating mechanism for retractable projecting members on board aircraits, a folding stay including two bars or tie members pivotally jointed together, driving means for folding said stay, a resilient bar parallel to the joint axis and secured to one tie member and a mechanism 1 adapted to transform a continuous rotation into an alternative one connecting the opposite end of the resilient bar to the other tie member to thereby produce an alternative rotation of this bar end in response to a continuous relative an- -gulaimotion of the tie members about the joint axis.

'9. Operating mechanism for retractable projectin'g members on board enemas, comprising a folding stay including at least two bars pivotally l jointedtogether, a gear wheel train including two end gear wheels both coaxial to the pivotal joint between said bars, one of said end Wheels being rotatably carried by one of said bars and the other end wheel is so tied to one bar that bOth the Wheel and bar will turn as a whole about the joint axis and a inotorcarried by a bar and so tied to the bar other than that tied to the end wheel that'inotor and bar will turn as a whole about the joint axis, said motor being connected to said r'otat'ably carried end wheel to rotate the latter.

10. Operating mechanism as in claim 9 wherein said motor is also coaxial to the joint between the bars. g

11. Operating mechanism as in claim 9 further comprising a speed reducer interposed between the motor and the said end wheel driven from the motor.

12. Operating mechanism for retractable projecting members on board 'aircra'fts, comprising 'a motor, a practically irreversible speed reducer driven from the motor and adapted to actuate the retractable member, means adapted to suppress in at least one direction of rotation the irreversibility imparted to the retractable member by the speed reducer, and control means driven from the motor to operate said previous named means in dependence on the motor running so that the irreversibility is suppressed during the time the motor is stopped.

13. Operating mechanism for retractable projecting members on board aircrafts, comprising a motor, a practically irreversible speed reducer driven from the motor and adapted to actuate the retractable member, means adapted to suppress in at least one direction of rotation the irre'- angers Versibillty' imparted t6 the retractable member by' the speed reducer, and c'entrifugally actuating means driven from the motor to operate said previous named means in dependence on the motor running.

14. Operating mechanism as in claim 12, fur ther comprising locking means of the retractable member in at least its service positions, said looking means being controlled also by said control means in such a way that said retractable mem-' her will be unlocked before the control means operate to lend irreversibility to the retractable member.

15. Operating mechanism as in claim 9, comprising a cylindrical housing carried coaxially to the joint by the bar which carries the motor, the latter being also coaxial tothe joint, a shaft driven from the motor and extending axially within said housing, transmission means between said shaft and the end wheel adapted to rotate independently of the bar by which it is carried, said housing being provided with an aperture through which projects said gear wheel train, a casing centered on said housing, the other end wheel of said train'being secured to said casing,

and connecting means between said casing and the other bar to cause them to rotate as a Whole.

16. Operating mechanism as in claim 9, comprising a cylindrical housing carried c'oaxially to the joint by the bar which carries the motor, the latter being also coaxial to the joint, a shaft driven from the motor and. extending axially within said housing, transmission means between said shaft and the end wheel adapted to rotate independently of the bar by which it is carried, said housing being provided with an aperture through which projects said gear wheel train, a casing centered on said housing, the other end wheel of said train being secured to said casing, connecting means between said casing and the other bar to cause them to rotate as a whole, in-- terlocking means between said housing and oasing to lock them against relative rotation, and control means of said interlocking means.

17. Operating mechanism for retractable projecti'ng members on board aircrafts, including two bars pivotally jointed together, driving means to angularly and relatively move said bars about their pivotal joint and a hydraulic shock-damper including a cylinder secured to one bar coaxial ly to said pivotal joint, and a movable member fitted within said cylinder to act therein as a piston and connected to the other bar to be moved within the cylinder in dependence on the relative angular displacement of the bars.

18. Operating mechanism as in claim 17, in

which saidmovable member is a rotatable diametral paddle, a, second rotatable diametral paddle pierced with holes, and two abutments provided in the cylinder on each side of said apertured paddle to engage and stop the latter in two predetermined positions.

19, Operating mechanism as in claim 12, further comprising a centrifugal friction clutch between the motor and the reducer.

20. Operating mechanism as in claim 9, wherein cooperating locking members are respectively carried by said bars for mutual grasping engage ment in the retracted position.

CHARLES RAYMOND WASEIGE- 

